The first known camels have been reported from rocks of upper Eocene age, and these small forms underwent considerable specialization of teeth and limbs as they developed in size. Many of the camels that lived during the middle Cenozoic had long legs which were well adapted to running and long necks which would have allowed the animals to browse on the leaves of tall trees. The earliest known Texas camels were found in rocks of Oligocene age, and camels, like horses, must have been abundant in Texas during the Pleistocene for their fossilized remains are common in many parts of the State. [Illustration: Plate 49 CENOZOIC MAMMALS] WOOLLY RHINOCEROS × ¹/₂₀ WOOLLY MAMMOTH × ¹/₄₀ BOOKS ABOUT FOSSILS The following books are recommended for the reader who wants to know more about fossils and fossil collecting. The publications listed below cover various phases of historical geology and paleontology and range from children’s books to the more technical publications of the professional paleontologist. This list, however, is by no means all-inclusive and many other interesting and useful publications are available. GENERAL WORKS Dunbar, C. O. (1959) Historical geology, John Wiley and Sons, New York. College-level text, well written and well illustrated. Moore, R. C. (1958) Introduction to historical geology, McGraw-Hill Book Co., New York. College-level presentation of earth history. Many illustrations of fossils. Moore, Ruth (1953) Man, time, and fossils, Alfred Knopf, New York. A readable account of fossils and their development throughout geologic time. Panghorn, M. W., Jr. (1957) Earth for the layman, American Geological Institute, Washington, D. C. Contains many valuable references. Raymond, P. E. (1950) Prehistoric life, Harvard University Press, Cambridge, Mass. College-level text. Richards, H. G. (1953) Record of the rocks, Ronald Press, New York. College-level earth history text. Simpson, G. G. (1953) Life of the past, Yale University Press, New Haven, Conn. Thorough, yet readable, introduction to paleontology. Stirton, R. A. (1959) Time, life, and man: the fossil record, John Wiley and Sons, New York. An introductory college text, most of which is of interest to adult level general readers. Note: _See also_ sections on Paleontology and Fossils _in_ Encyclopedia Americana, Encyclopaedia Britannica, and others. NONTECHNICAL AND JUVENILE Andrews, R. C. (1953) All about dinosaurs, Random House, New York. Interesting and readable dinosaur book for junior high and high-school age. Andrews, R. C. (1956) All about strange beasts of the past, Random House, New York. Interesting and easy to read, this book deals largely with extinct and unusual mammals (junior high and high school).